3D Rigid Body Impact Burial Prediction Model

Falling of rigid body through air, water, and sediment is investigated experimentally and theoretically. Two experiments were conducted to drop rigid cylinders with the density ratio around 1.8 into shallow water (around 13 m deep) in the Monterey Bay (Exp-1) and into the Naval Postgraduate School’s swimming pool (Exp-2). During the experiments, we carefully observe cylinder track and burial depth while simultaneously taking gravity cores (in Exp-1). After analyzing the gravity cores, we obtain the bottom sediment density and shear strength profiles. The theoretical work includes the development of 3D rigid body impact burial prediction model (IMPACT35) which contains three components: triple coordinate transform, hydrodynamics of falling rigid object in a single medium (air, water, or sediment) and in multiple media (air-water and water-sediment interfaces). The model predicts the rigid body’s trajectory in the water column and burial depth and orientation in the sediment. The experimental data (burial depth, sediment density and shear strength) are used to evaluate the newly developed numerical model. The 3D model shows great improvement to the currently used US Navy’s 2D model (i.e., IMPACT28)